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Second, the value of F2 for the Mono vowel = provides evidence that that is the
correct symbol to use in transcribing the sound. The mean value of F2 is 1292 Hz, which
is higher than the value of F2 in the vowel ) of a typical male American English speaker
(~1100 Hz), but lower than the value of F2 in the vowel 3 of a typical American English
speaker (~1660 Hz, Ladefoged 1982: 176).
Of course, these observations are based on the assumption that the vowel space of
the Mono speaker correlates with the average vowel space of a male speaker of American
English. Unfortunately, as of yet, a foolproof method of normalizing such data has yet to
be developed. Ladefoged (1982: 195-6) admits that “[P]honeticians do not really know
how to compare acoustic data on the sounds of one individual with those of another.” He
suggests two possible approximations: (1) use the average value of F4 as an
approximation of an individual’s head size, or (2) assume that “each set of vowels is
representative of the complete range of a speaker’s vowel qualities.”
In the case at hand, the average F1 and F2 values for i and u are approximately the
same for American English and Mono, as shown in (4), so the assumption that the vowel
space is the same is a reasonable approximation.
(4) English Mono (Speaker 1)
F1 F2 F1 F2
i 280 2250 272.5 1940
u 310 870 270 897.5
Finally, note that there is separation between = and its allophonic variant [. This
provides acoustic support for raising process exemplified in (15) of Section 2.2.
For comparison, Figure 8.33 shows each Mono vowel spoken in isolation.
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